The word ‘faith’ often trips up people who are outside Christianity (and, indeed, some inside of it), because it is a word with multiple meanings. What are some of those?
1. Faith as in a spiritual life. ‘My faith life …’ = ‘My spiritual life …’
2. Faith as in a religion. ‘My faith teaches that …’ = ‘My religion teaches that …’
3. Faith as in conditional belief, which will become warranted upon confirmation. ‘First, have faith in God, then …’ This is typically used when talking about developing a relationship with God, and so refers to having faith in the character of God. God seems to be saying you should do x, but is x really going to have good results? So, conditionally, act on x, and then see what the result is. If the result is good, your faith will be confirmed. You have reason to act because many others have, and testify to the results, say.
However, it can also be used when talking about faith in the existence of God, and proceeds in a similar way. How do I know there is a God? Well, listen to Him and act on his advice. Judge by the results you get. And so on.
4. Faith as in knowledge, obtained often through religious experience. ‘I know there is a God by faith …’, as in the ‘light’ of the ‘Holy Spirit’ which enters ones and gives (say) a direct knowledge of God and the existence of ‘Heaven’, typically in a dramatic experience of ‘conversion’. (This sort of experience happens to many Christians.)
Similar to 3., this can also apply not only to the existence of God, but his character, as typically an experience of this sort involves that there is a God and something about what kind of God He is (a God of ‘light’, or goodness, and so on – these are attributes perceived in the experience, and they are perceived as belonging to something, i.e., ‘God’).
As mentioned above, however, some Christians misunderstand the proper use of this word (as also happens in regular language, where people use a word mistakenly). For example, they will (perhaps lazily) invoke it to ward off criticism, saying they know something simply by faith, where it is construed by the would-be critic as blind faith – simply believing something without any (epistemological) reason for doing so. A similar situation might apply to, say, 3. above, where a person thinks the Christian is advocating blind ‘faith’ in God, without an appeal to any consequent empirical verification! Of course, that doesn’t make any sense, and so the Christian is disregarded.